The present invention relates to an apparatus and method for inspecting defects, contamination, and other foreign substances present on minute patterns formed on a substrate through a thin-film process represented by a semiconductor manufacturing process and a flat-panel display manufacturing process.
A conventional apparatus for inspecting defects in semiconductors is disclosed in, for example, International Patent Publication WO2003/0069263. The conventional inspection apparatus described in WO2003/0069263 illuminates the surface of a wafer obliquely with laser light, and after the light has been scattered from the wafer surface, captures the scattered light by use of an objective lens disposed above the wafer. The scattered light that has been captured is detected according to the particular scattering angle by a plurality of detectors. Detection images that have thus been obtained are compared with images of adjacent dies in order to detect defects.
Another known apparatus for inspecting defects in semiconductors is disclosed in, for example, JP-A-2000-105203 (Patent Document 2). According to Patent Document 2, during defect inspection of an inspection object (semiconductor wafer) having an array of LSI chips each provided with a register group region and memory block region including an iterative pattern formed thereon, and with a CPU core block region and input/output block region including a non-iterative pattern formed thereon, an optical system for darkfield illumination illuminates the wafer with slit-shaped beams of mutually different wavelengths obliquely from different directions within a horizontal plane, and an optical system for darkfield detection detects defects present on a dielectric film such as an oxide film. It is also described in Patent Document 2 that the optical system for darkfield detection includes an objective lens, a spatial filter formed by a recurrence of an iterative light-shielding pattern, an ND filter, a polarizer, a branching optics (beam splitter) formed to split the beam of light reflected from the inspection object after being passed through the spatial filter, the ND filter, and the polarizer, and increase the intensity of one of the reflected beams branched by the branching optics, to substantially 1/100 of the intensity of the other reflected beam, and a plurality of image sensors (detectors) each for receiving each reflected beam split by the beam splitter. In addition, it is described in Patent Document 2 that the ND filter, when disposed behind the beam splitter, can conduct independent control of the intensity of each beam of light incident upon two detectors.